Drug delivery systems for delivering drugs to the oral mucosa include tinctures, buccal formulations and ointments. Tinctures are easily applied to oral lesions but may be ingested into the body within a relatively short time after application. Buccal formulations may be retained in the oral cavity for longer periods than tinctures; however, they are usually larger in size and thus uncomfortable to retain in the oral cavity and often cause tissue irritation. In addition, they may be separated from lesions by saliva or other exudate. Conventional ointment formulations may be readily applied. However, in many cases, they also may be readily removed from the oral cavity by mechanical movement of the oral tissue such as during speaking or eating. In addition, conventional ointments may bleed during storage or even after application. Moreover, bleeding of active ingredients from ointments after application to oral lesions may cause active ingredients to be separated from such lesions and carried by saliva to other locations in the oral cavity.
A discussion of prior art patents relating to various drug delivery systems including oral delivery systems and/or oral adhesives follows.
U.S. Pat. No. 3,029,187 to Steinhardt discloses anhydrous adhesive pharmaceutical vehicles specifically designed for adhering active ingredients to the oral mucosa which vehicles are formed of an intimate mixture of gelatin and a topically-acceptable vehicle such as petrolatum, lanolin, benzoinated lard, hydrogenated cotton seed oil, carboxymethyl cellulose, pectin, karaya gum, tragacanth, Irish moss extracts, alginates, polyvinyl pyrrolidone, carbo gum, guar gum and pre-treated water-soluble starch. Active ingredients which may be carried by such vehicles include antiseptics, anesthetics, steroids, hormones and antibiotics.
U.S. Pat. No. 3,029,188 to Cyr et al discloses gelatin oral adhesive pharmaceutical preparations which include an intimate admixture of particulate gelatin with mineral oil containing thickening agent, such as polyethylene, dispersed therein. Cyr et al indicate that portions of the gelatin may be substituted by other gums such as carboxymethyl cellulose, pectin, karaya gum, tragacanth, Irish moss extracts, alginates, polyvinyl pyrrolidone, carob gum, guar gum and pre-treated water-soluble starch.
U.S. Pat. No. 3,312,594 to Cyr et al discloses a long-lasting troche which contains a medicament and equal portions of pectin, gelatin and carboxymethylcellulose; the troche interacts with saliva to dissolve in the mouth to form an adhesive composition which secures and retains the medicament to the oral mucosa.
U.S. Pat. No. 3,984,571 to Chen discloses a liquid carrier for a diagnostic or therapeutic agent which liquid carrier includes a fine particle size hydrocolloid, such as a cellulose ether, suspended in a non-aqueous water-immiscible mobile liquid. When a composition containing the diagnostic or therapeutic agent in the liquid carrier is made to contact a moist surface, the mobile liquid is drained off and the hydrocolloid (carrying the diagnostic or therapeutic agent) attaches itself to the surface.
U.S. Pat. No. 4,542,020 to Jackson et al discloses antifungal suppository formulations which are substantially free of water which include an antifungal agent such as nystatin together with a hydrocolloid, such as sodium carboxymethyl cellulose or hydroxypropylmethyl cellulose and a low melting suppository base.
U.S. Pat. No. 4,540,602 to Motoyama Shimesu et al discloses a process for preparing a pharmaceutical composition containing a solid drug in the form of finely divided particles no greater than 10 microns in diameter, wherein a solid drug which is substantially water-insoluble is dissolved in a low-boiling hydrophobic organic solvent, the resulting solution is emulsified in water in the presence of a water-soluble high molecular weight substance which is hydroxypropyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl ethyl cellulose, carboxymethyl cellulose sodium salt, alpha-starch, hydroxypropyl starch, pullulan, gum arabic, tragacanth gum, gelatin, polyvinyl alcohol, polyvinyl pyrrolidone and mixtures thereof and water is thereafter removed.